[tor-dev] Proposal: Controller events to better understand connection/circuit usage

[Damian Johnson]

> I wonder if we should avoid restricting connection types in the spec by
> defining this argument as connection type _string_ as opposed to an
> enumeration.

That depends on how volatile you think it'll be. If it's reasonably
static then an enumeration would probably be best.

> Has the advantage that we don't have to touch the spec whenever
> we add another connection type.  Does that make sense?

True, but that also means that event recipients have no idea what kind
of values to expect or what they mean.

> A fine question.  Here are two examples of this event:
> ...

Ah, I see. That does make it trickier.

I'm not spotting any precedent for doing multiple sub-mappings in an
event. Doing this in positional arguments is simple to parse, but
beside the lack of flexibility mentioned earlier it's pretty hard to
read.

I cringe a bit to suggest it, but maybe a mapping in a mapping?

CELL_STATS PCircID=8 PConnID=47110 PAdded=created:1,relay:1
PRemoved=created:1,relay:1

> Sure, sounds doable.  Will fix that.

Thanks!

> Want to suggest new event
> formats with keyword arguments to make them easier to parse by Stem and
> friends?

Positional arguments aren't harder to parse, just harder to read and
more inflexible. I'd be happy to suggest spec alternatives if you
want. Mind if we revise the proposal based on the above first?

Cheers! -Damian